Algae have been recognized as a potential source for ‘green’ fuels, in particular biodiesel. Algae are not typically used as food products but can be easily produced in large quantities and have therefore attracted attention for their potential use as fuels. A problem associated with harvesting the valuable oils present in the algae is the energy consumption associated with removing the excess water and the breaking (lysis) of the cell walls to extract the oils. Many mechanical processes for cell wall destruction are known such as centrifugation, mechanical pressure, often combined with elevated temperatures. A relatively recent method uses ionic liquids to effectively dissolve the cells walls thereby releasing the oils within the cells. However, also here the majority of the water needs to be removed to provide the desired ionic liquid strength.
Ionic liquids however are often quite expensive and difficult to produce and are difficult to separate from the reaction mixture and thus hard to recycle. Another problem is that often emulsions are formed which are very difficult to break which makes it difficult to separate the water phase from the oil phase. This problem occurs in particular at higher levels of water (i.e. lower concentration of algae).
It is desired to provide a method for treating algae, which is economical and does not have the herein-above mentioned disadvantages. It is desired that the method allows easy separation of different phases and efficient recycling of the ionic liquid. It is also desired that the method can be applied to wet algae and be effective even at high water content.